The present invention relates to a retaining shoe configuration and its use in a packer, frac plug, or bridge plug in downhole applications.
In the drilling or reworking of oil wells, a great variety of downhole tools are used. For example, a packer may be used to support production tubing and other completion equipment, such as sand control assemblies adjacent to a producing formation, and to seal the annulus between the outside of the production tubing and the inside of the well casing to block movement of fluids through the annulus past the packer location. Packers are commonly run into the wellbore on a conveyance such as a wireline, work string, or production tubing.
Typically, packers may have an upper and a lower set of anchor slips with opposed camming surfaces, which cooperate with complementary opposed wedging surfaces, whereby the anchor slips are outwardly radially extendable into gripping engagement against the well casing bore in response to relative axial movement of the wedging surfaces. Packers may also carry annular seal assembly including one or more seal elements, which are radially expandable into sealing engagement against the bore of the well casing in response to axial compression forces.
Prior to actuation and the subsequent radial expansion of the seal elements, many adverse environmental conditions may exist around the outer diameter of the seal elements. For example, certain completion operations, especially those in a horizontal wellbore, require fluids to be circulated in the annulus between the well casing and the packer at high rates. It has been found that such high flow rates of wellbore fluids may create a low pressure region around and adjacent to the outer diameter of the packers and the seal elements. It has also been found that this low pressure region may cause the seal elements to prematurely expand, thus causing the packer to set.
Therefore, a need has arisen for a packer that is capable of being deployed in adverse environments such that its seal elements are not affected by the adverse environments, such as high circulation rate fluids, prior to setting the packer.